Defensive linemen Justin Smith and Ray McDonald, as well as cornerbacks Tramaine Brock and Chris Culliver were in pads at the beginning of the team’s practice on Wednesday.

Also, receiver Michael Crabtree was dressed for practice at the beginning of individual drills. Crabtree has been out since leaving practice with a hamstring strain on July 30.

Linebacker Patrick Willis was not in pads at the beginning of practice.

Smith (shoulder) and McDonald (biceps) underwent offseason surgery. Brock has missed extended time with an ankle sprain. And Culliver has sat out several practices as a precaution, according to defensive coordinator Vic Fangio, after missing the season with a knee injury.

Williams said he was looking to returning to practice from a broken left lower leg he sustained in Week 2 of last season. Physically, he feels fine, but he said there are other aspects of returning from injury that creates a challenge.

“Running around and cutting and everything like that, that’s the easy part,” Williams said. “Anybody can do combine drills. But when you’re pushing against somebody 300, 350 pounds, that totally different than running the 40.

“When they activate you off PUP, that’s the paper hurdle. You still have to get over the mental hurdle.”